ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus PublicationsGöttingen, Germany10.5194/acp-7-5207-2007Characterization of Polar Stratospheric Clouds with spaceborne lidar: CALIPSO and the 2006 Antarctic seasonPittsM. C.1ThomasonL. W.1PooleL. R.2WinkerD. M.11NASA Langley Research Center, Hampton, VA, USA2Science Systems and Applications, Incorporated, Hampton, VA, USA1010200771952075228This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article is available from http://www.atmos-chem-phys.net/7/5207/2007/acp-7-5207-2007.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/5207/2007/acp-7-5207-2007.pdf

The role of polar stratospheric clouds in polar ozone
loss has been well documented. The CALIPSO satellite mission offers a new
opportunity to characterize PSCs on spatial and temporal scales previously
impossible. A PSC detection algorithm based on a single wavelength threshold
approach has been developed for CALIPSO. The method appears to accurately
detect PSCs of all opacities, including tenuous clouds, with a very low rate
of false positives and few missed clouds. We applied the algorithm to CALIOP
data acquired during the 2006 Antarctic winter season from 13 June through
31 October. The spatial and temporal distribution of CALIPSO PSC
observations is illustrated with weekly maps of PSC occurrence. The
evolution of the 2006 PSC season is depicted by time series of daily PSC
frequency as a function of altitude. Comparisons with "virtual" solar
occultation data indicate that CALIPSO provides a different view of the PSC
season than attained with previous solar occultation satellites.
Measurement-based time series of PSC areal coverage and
vertically-integrated PSC volume are computed from the CALIOP data. The
observed area covered with PSCs is significantly smaller than would be
inferred from the commonly used temperature-based proxy <I>T</I><sub>NAT</sub> but is
similar in magnitude to that inferred from <I>T</I><sub>STS</sub>. The potential of
CALIOP measurements for investigating PSC composition is illustrated using
combinations of lidar backscatter and volume depolarization for two CALIPSO
PSC scenes.